short-path problem (Spfa) 分类： ACM TYPE 2014-09-02 00:30 103人阅读 评论(0) 收藏

#include <cstdio>
#include <iostream>
#include <cstring>
#include <queue>
#include <vector>
using namespace std;
#define INF 0x7fffffff
struct edge
{
    int t;
    long long d;
};

vector<edge> g[20005];
int n, m, p, q;

void Spfa(int x)
{
	int minn = 0;
	
    queue<int>q;
    long long dis[20005];
    bool vis[20005];
    memset(vis,false,sizeof(vis));
    
    for(int i = 0; i <= n; i++)
    	dis[i] = INF;
    	
    vis[x] = true;	
    dis[x] = 0;
    q.push(x);
    
    while(q.size())
    {
    	int tmp = q.front();
    	q.pop();
    	vis[tmp] = false;
    	
    	for(int i = 0; i < g[tmp].size(); ++i)
    	{
    		if(dis[g[tmp][i].t] > dis[tmp] + g[tmp][i].d)
    		{
    			dis[g[tmp][i].t] = dis[tmp] + g[tmp][i].d;
    			if(vis[g[tmp][i].t] == false)
    			{
    				q.push(g[tmp][i].t);
    				vis[g[tmp][i].t] = true;
    			}
    		}
    	}
    }
    
    for(int i = 2; i <= n; ++i)
    {
    	cout<<dis[i]<<endl;
    }
    
}


int main()
{
		memset(g,0,sizeof(g));
		
		cin>>n>>m;

		q = 1;
			
		for(int i = 0; i < m; ++i)
		{
			int x, y, s;
			edge e;
			cin>>x>>y>>s;
			e.t = y;
			e.d = s;
			g[x].push_back(e);
		}

		Spfa(q);		

    return 0;
}

算法训练 最短路

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